The Great Ball Contraption

Build a machine out of Lego that takes Lego soccer balls from an input hopper to an output hopper at a minimum rate of one per second by any means you can devise. Define a standard interface for this kind of machine so that the output of one will reliably feed the input of the next. Now invite hundreds of Lego fanatics to use their imagination to build modules of all different sizes and types to meet this standard – then connect them all end to end to make the biggest Rube Goldberg contraption in history. Thanks Steve! Link.